Your Country’s Call. Isn’t this worth fighting for? Enlist Now’, 1915. Chromolithograph recruiting poster, published as Number 87 by the Parliamentary Recruiting Committee, printed by Jowett and Sowry, 1915. Propaganda posters played an important role in encouraging people to support the war. In 1914 Britain had a small professional army. As World War One (1914-1918) progressed more men were needed. By December 1915, over two million men had voluntarily joined up. Despite this, Britain was still forced to introduce the call up in January 1916, when the Military Service Bill provided for the conscription of single men aged 18 to 41. In May 1916 conscription was extended to married men as well.